Matt Damon, Olivia Wilde, Bono, and Richard Branson are trying to end the world water crisis ... one toilet at a time.

As Matt said back in February when he started the movement, he and his pals "won’t go to the bathroom until everyone in the world has access to clean water and sanitation." New Hollywood A-listers, including Olivia, Bono, and Richard, recently joined Matt's "toilet strike."

The strike -- led by Matt's advocacy group Water.org -- is intended to end the water crisis that has left 780,000,000 million people -- one in nine -- without access to clean water and sanitation.

The stars tried to use humor to lighten the severity of the situation in a new public service announcement.

"I remember when Matt first brought up the idea, it was at a meeting of the Illuminati," perennial activist Bono said.

Wilde joked that Bono was mad that she joined the elite group of celebs involved with the movement, "Bono was so mad. I only got in because I am an android from the future."

Damon closed the video by encouraging others to join the strike. "And remember, if you don't use the toilet, you're a celebrity," he said.

For other information about the cause or to make a donation, visit water.org or strikewithme.org.